1992 Honda Accord transmission does'nt work properly

130,000 MILES • 4 CYL • FWD • AUTOMATIC
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JOHN241980
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my 92 accord has been running on 1st and 2nd gear most of the time, some 2nd and 3rd with the d4 light on ..so i have been driving it like a stick shift for some time now..so i took it to aamco recently and they told me to replace the whole transmission..i wasn't going to do that..then couple of days ago my friend told me to disconnect the negative cable of the battery before shutting of the car and connecting it back before starting the car ...that worked for a couple days but now only sometimes..so i am pretty sure its the control unit....otherwise do tell me if its something else..

I have 2 questions about the control unit

1 after replacing the unit, is there anything else that i need to do on the car.. like resetting something to be compatable with the replacement?

2 Is there a way to repair the unit itself for less cost?
Dec 2, 2009 at 1:22 PM
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KHLOW2008
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Hi john241980, It could be the control unit or some other sensors causing the problem. Retrieve the trouble code and let me know what it is.


https://images.2carpros.com/forum/automotive_pictures/192750_SCS91Accord_14.jpg

Use a jumper wire to bridge the SCS and turn ignition switch ON. The D4 light should start blinking and pausing. Count the number of blinks and let me know what it is. If the D4 lights stays on without any blinks with SCs bridged, the control unit is faulty and you can try getting a used or reman unit.
Dec 5, 2009 at 10:04 PM
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CHAVARES
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Thanks for your reply. I bridged the SCS and D4 light was off. What can be the problem? is the TCU? Thanks![ quote="KHLow2008"]Hi john241980, It could be the control unit or some other sensors causing the problem. Retrieve the trouble code and let me know what it is.


https://images.2carpros.com/forum/automotive_pictures/192750_SCS91Accord_14.jpg

Use a jumper wire to bridge the SCS and turn ignition switch ON. The D4 light should start blinking and pausing. Count the number of blinks and let me know what it is. If the D4 lights stays on without any blinks with SCs bridged, the control unit is faulty and you can try getting a used or reman unit.[/quote]
Jan 9, 2010 at 4:39 AM
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KHLOW2008
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Did the Check Engine Lamp stay on or blinked when the SCS was bridged and the ignition switch turned ON?

Do you have a S mode indicator light and did it blink when the above was performed?
Jan 9, 2010 at 4:21 PM
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CHAVARES
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Thanks!

The check engine light stays on but didn't blink. I don't have a S mode indicator only the D4.

Regards.
Jan 11, 2010 at 12:36 PM
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KHLOW2008
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There are 2 possiblre causes for the problem and they definitely are not caused by the transmission.

1. Faulty TCU. You can get a reman or used unit for a reasonable cost.

2. Faulty Throttle Position Sensor. At times a faulty TPS does not throw any trouble codes but it is operating out of range and would cause non shifting, except between 1st and 2nd.

If you are able to do test with the aid of a DVOM, you can determine if the TPS is faulty. For TCU fault as it does not throw any codes, the only thing you can try is to get a substitution unit or remove the unit to check the circuit board for leaking capacitors.
Jan 11, 2010 at 10:34 PM
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CHAVARES
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Thanks! I checked the TCU and seems that is burned so I ordered a refurbished already. I just have another question before I proceed and change the TCU. Now I ´m getting the brake light on, usually when this happens I started to have more problems with the transmission and the stick is locked can this issue be related with the problem that causes that problem with TCU is burned? Thanks!
Jan 26, 2010 at 11:41 AM
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KHLOW2008
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The brake lights staying on would be due to a bad brake switch stopper ( rubber plug ) located on the brake pedal for turning the brake switch off when pedl is not depressed.

If the brake lights are erratic and intermittently not working, it would cause the interlock system to fail and not allow you to shift out of park.

The brake light circuit is part of the interlock system which allows you to shift out of park only when the ignition switch is turned ON and brake pedal is depressed. If it does not work, check if the brake lights are turning on when brake peda is depressed. If not, the brake switch is bad and requires replacement.

This circuit is not linked to the TCU and would not cause it to fail. The TCU shorting internally could be due to shorting of the wiring circuit and/or shift solenoids. Check the shift solenoid wires at transmission at front portion near the radiator.
Jan 27, 2010 at 3:22 AM
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